12 ga is just a bore size, the load itself is what you need to look at. A 12 ga shooting a reduced or light target load won't kick much. As for the actual shotgun size, find a used Rem 870 and take it and your DW to a shop that works on shotguns and can fit the gun to her. Fit is key to a shotgun not kicking. Not kicking is key to taking a novice and getting them to shoot enough to start shooting well. FWIW, $.02

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Better is the Enemy of Good Enough.
Okay, what’s your point??